I would like to add one thing in case anyone else has encountered the same issue. Email notifications started using the wrong template after the upgrade.
It appears the install renames the Email.vm and drops a new default version on ESM.
A simple rename of the new Email.vm to Email.vm.old and renaming your correct Email.vm.xxxx back to Email.vm corrects the issue.
This feels like something that should be addressed in the documentation as it is an undesired effect.